Top 12 Open-Source Alternatives to Citadel

Product categories

Analytics Appointments and Scheduling Calendar Data Dashboard Email Email Clients Email Service Provider Enterprise Communication IoT Platform Product Analytics SMTP Server Self-hosted Email

Summary

The top open-source alternatives to Citadel are iRedMail, Roundcube, and SOGo. One of the criteria for ordering this list is the number of mentions that products have on reliable external sources. You can suggest additional sources through the form here.

iRedMail Landing Page
1

iRedMail

A fully fledged, free email server solution, an open source project (GPL v2).
Pricing:
- Open Source
#Email #SMTP Server #Self-hosted Email 2 social mentions
Roundcube Landing Page
2

Roundcube

Web-based IMAP email client
Pricing:
- Open Source
#Email #Email Clients #SMTP Server 16 social mentions
SOGo Landing Page
3

SOGo

SOGo is groupware server with a focus on scalability and open standards.
Pricing:
- Open Source
#Email #Email Clients #Self-hosted Email 1 social mentions
mailcow Landing Page
4

mailcow

An open source mailserver suite.
Pricing:
- Open Source
#Email #Self-hosted Email #Email Service Provider 82 social mentions
Rainloop Landing Page
5

Rainloop

RainLoop is a web based email client.
Pricing:
- Open Source
#Email #Email Clients #Email Management
Exim Landing Page
6

Exim

Exim is a message transfer agent (MTA) developed at the University of Cambridge for use on Unix systems connected to the Internet.
Pricing:
- Open Source
#SMTP Server #Email #MTA
Mail-in-a-box Landing Page
7

Mail-in-a-box

Mail-in-a-Box provides webmail and an IMAP/SMTP server for use with mobile devices and desktop mail software and also includes contacts and calendar synchronization.
Pricing:
- Open Source
#Email #Self-hosted Email #Email Service Provider 115 social mentions
ThingSpeak Landing Page
8

ThingSpeak

Open source data platform for the Internet of Things. ThingSpeak Features
Pricing:
- Open Source
#Data Dashboard #IoT Platform #Analytics 9 social mentions
Squirrelmail Landing Page
9

Squirrelmail

SquirrelMail is a standards-based webmail package written in PHP.
Pricing:
- Open Source
#Self-hosted Email #Enterprise Communication #Email 3 social mentions
Radicale Landing Page
10

Radicale

The Radicale Project is a complete CalDAV (calendar) and CardDAV (contact) server solution.
Pricing:
- Open Source
#Email #Email Clients #Network & Admin 15 social mentions
Nextcloud Calendar Landing Page
11

Nextcloud Calendar

The Calendar app is a user interface for Nextcloud's CalDAV server.
Pricing:
- Open Source
#Calendar #Appointments and Scheduling #Email 4 social mentions
Particle.io Landing Page
12

Particle.io

Particle is an IoT platform enabling businesses to build, connect and manage their connected solutions.
Pricing:
- Open Source
#Data Dashboard #IoT Platform #Analytics 9 social mentions